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. Author manuscript; available in PMC: 2010 Sep 16.
Published in final edited form as: Dev Biol. 2007 Aug 9;310(2):388–400. doi: 10.1016/j.ydbio.2007.08.002

Figure 5.

Figure 5

A dorsal/ventral boundary to cellular migration in the limb bud mesenchyme. (A) Summary of dorsal/ventral CHAPOL analysis of chicks harvested at HH35. Stages of embryo injections are listed on the left. Clones are classified as dorsally restricted (Dorsal), Ventrally restricted (Ventral), Unassignable due to the presence of cartilage and/or perichondrium cells in clone (Neither), or as boundary crossing (Mixed). Numbers presented are formatted as [number of clones: smallest clone-largest clone (average clone size)]. (B) Whole mount in situ hybridization for Lmx1b, shown by blue staining in cross-section at limb bud level, demonstrates the dorsally restricted expression domain. (C, D) Embryos injected with CHAPOL library at stage HH11 (labeling lateral plate mesoderm at stage HH16) produced clonally related cell populations predominantly localized to either the dorsal (Lmx1b positive), or ventral (Lmx1b negative) domains. Examples examples shown are clusters of PLAP positive cells containing ventrally restricted (C) and dorsally restricted (D) clones that span their respective domains but fail to cross the lmx1b demarcated boundary. Lmx1b expression is in brown to distinguish from retroviral PLAP staining. (E–H) show a separate clone that extends along the proximal distal axis of the limb skirting the edge of the Lmx1b demarcated D/V boundary but remaining firmly in the ventral Lmx1b negative domain. Clonally related cells are labeled with black arrowheads and green pseudocoloring of the dissected regions. (E′–H″) show magnified views of the boxes in E–H. The D/V boundary is illustrated with a dashed line. (I) Summary of dorsal/ventral CHAPOL data analysis of chick embryos injected at HH11 and harvested at HH24. (J–M) Tantalum foil barriers implanted between HH15 somites and lateral plate mesoderm block lmx1b induction. Embryos shown were surgically manipulated to either completely block the limb field (J,K) or partially block (L,M) the midline originating signals specifying the dorsal right hind limb mesenchyme. Partial blockages allow induction of lmx1b only in the unblocked region of the limb bud. All embryos in J–M were hybridized with probes detecting lmx1b transcript.